Range-finder.



C. M'cN. FROST.

vRANGE FINDER.

APPLICATION FILED IuLY 23,1915.

l l 96,77 1 Patented Sept. 5, 1916.

J7@ Q Z- g GMM wmfmwwmwsv the location and therefore range and azimuth'CHARLES MGNAUGHTON FROST, SAN DIEGO, CALIFORNIA.

RANGE-FINDER.

Specification of Letters Patent.

Patented Sept. 5, 1916.

Application filed July 23, 1915. Serial N0. 41,508.

To all whom t may concern Be it known that I, CHARLES MGNAUGH- 'roN FRosT, a citizen of the United States, residing at San Diego, in thecounty of San Diego and State of California, have invented a new anduseful Range-Finder, of which the' following is a specification. Thisinvention relates to means for mechanically predetermining on a plottingboard the indicated coincident positions of a moving target and aprojectile, and its object is to ena-ble the plotter to locate thisposition in the shortest possible period of time.

This invention consists, in combination with a base, a series ofpointers movable relative to each other in a straight line, and anadjusting device for separating the pointers consisting of a memberpivoted intermediate its ends, a projection thereon on one side of thepivot for moving one of the pointers away from the second pointer, anadjustable Contact on said member on the other side of the pivot formoving the third pointer from the second, and means for shifting saidprojection.

In the accompanying drawing, Figure 1 is a plan and Fig. 2 is a centralvertical section of this improved range finder. Fig. 3 is a plan of therange finder with the pointers in operable Position. Fig. 4L is asection on the line 4 1 of Fig. 1.

Similar reference characters refer to like parts throughout the severalviews.

In coast artillery work, to which this instrument is peculiarly adapted,the area pro` tected by any particular gun may be shown on a plottingboard whereon the distances are represented on any desired scale.Straight edges may be pivoted at proper points representing observingstations, and each will be furnished with a special protractor orazimuth circle so that the location of the moving target can beaccurately plotted at each observation. As these observations are takenat definite time intervals, usually of half a minute, and immediatelyplotted, the speed and course of the target is` determined with greataccuracy. At a third point on the plotting board, representing a gunposition, may be mounted a graduated straight edge and specialprotractor or azimuth circle by means of which the range and azimuth ordirection of the target relative to the gun position may be measured.l/Vhile of the target at each observation are thus determined, and afterseveral observations the location, range and azimuth of the target atthe next observation time can be accurately predicted, the determinationof the range and azimuth of the target at the instant a shell fired fromthe gun at an observation time should reachthe target, presents a moreserious problem, for if a series of dots eight-tenths of an inch aparton a board, whose scale is three hundred yards per inch, represents thelocations of a target at half minute intervals, the target is movingabout 16.36 miles per hour. If the target is 10,000 yards distant, aprojectile having an average speed of 1750 feet per second would requireover seventeen seconds to travel to the target, at which time the targetwill have movedmore than 125 yards from the location predicted for thetime of firing. The distance; A of this set-forward point from the lastobserved location is therefore about hand corner permits the instrumentto be f readily positioned on the plotting board. Transversely slidableon the base are two plates 5 and 6 provided with transverse ribs 7 thataccurately fit the groove 2, and are at right angles to the inner edgesof these plates. Each of the plates may have a pointer 8 9 or a stylus10-11, or both. Each stylus is preferably of spring steel with a sharppoint 18 and a knob la whereby the point of the stylus can be readilyforced into the paper of the plotting board.

rlhe actuating member 16 is'mounted on the bolt or pin 17, and ispreferably held in position by a nut 18. At its front end is a dependingcylindrical lug 19 extending down between the adjacent edges of theplates 5 and 6. Small coil springs 20 connect to this member 16 and topins 22 on the plates and tend to normally hold the parts in theposition shown in Fig. 1. This operating member 16 is formed with a slot23, in which is slidable a nut 24E having a depending cylindrical lug25, which also extends between the plates 5 and 6. 1t is desirable thatthe lugs 19 and 25. shall be of the same diameter and be in alinementwith the pin 17 and the slot 23. A screw 26 is mounted in this nut andis formed with a circumferential groove 27 into which the yoke 28extends. r1`his yoke is secured across the outer end of the slot 23 andacts as a thrust bearing for the screw. Any other desired means may beemployed for adjusting the lug 25 in the plane of the lug 19 and pin 17.This screw may have a knob 29 at its outer end so that it can be turned.The -top of the member 16 may be graduated, as shown in Fig. 1, so thatthe cross mark 30 on the nut 24E and therefore the lug 25, may bepro-perly positioned. r1`he distance from the line 0 on the member 16 tothe pin 17 is the same as the distance from this pin to the center ofthe lug 19. Nhen the cross mark 30 is at 0, and the member 16 is swung,the pointers 8 and 9 will be moved equal distances from the pointer 3.1f now the target spoken of before were at the gun position, the time offlight would be 0, and the set-forward point would be at the predictedpoint. 1f the target were 12,000 yards distant at the last observationand moving` toward the right, the screw is turned until the line 30 isat the 12000 mark. r1`he point 3 is then placed on the last determinedlocation of the target on the plotting board and the member 16 is swungand the base 1 is turned until the pointer S or stylus 10 is at the neXtprevious location of the target. The stylus 11 is then depressed and itspoint 13 will indicate the set-forward point, that is the location ofthe target at the time a shell fired at the next observation time at theproper range and azimuth reaches this Setforward point.

It must be understood that each of these range finders must be graduatedfor the particular gun whose firing is to be controlled, for the time offlight will depend upon the muzzle velocity and upon the trajectory andweight of the projectile. As previously? stated, the distance betweenthe set over point and the last observed location will be tance Y.

Y Va

to the-right. The distance between the pin 17 and the line indicating12,000 yards will times the distance between the pin 17 and the lug 19.1f the time of flight of the projectile of a ten-inch gun of 1895 modelfor 12,000 yards is 2211,- seconds, then the distance from the pin 17 tothe line marked 12,000 will be 1.75 the distance between this pin andthe lug 19, and when swung as shown in Fig. 3, the member 16 willmovethe pointer 9 threefourths farther than the pointer 8. rEhetime offlight for each range for each gun must be fully determined in advanceand the graduations on the member 16 can then be accurately establishedby simple calculations. v 1t is evident that graduations may be placedat both sides of the slot 23 so that the instrument may be used fordifferent guns. rlhe points-3, 8, 9 and 13 should be sharp so as tointerfere with each other as little as possible. The size of theinstrument will depend upon the scale of the plotting board and must besuch that the pointers 8 and 9may be moved far enough to indicate theset-forward point for the swiftest vessels at the longest vrange of thegun with which the instrument is to be used.

l claim 1. 1n a range finder, the combination of a base having apointer, a pair of plates slidably mounted thereon and each having apointer, an operating member pivotally mounted intermediate its ends onthe base and provided with two lugs engaging said plates, and means foradjusting one of thc lugs.

2. In a range finder, the combination of a base having a pointer, a pairof plates mounted on the base and each having a pointer normallyadjacent the pointer on the base, said plates being slidable on the basein such a manner that the pointers remain in substantially the samestraight line, an operating member pivotally mounted on the plate andprovided with two lugs engaging said plates, one of the lugs beingadjustable in a plane passing through the pivot and the other lug, andmeans for adjusting said lug.

3. 1n a range finder, the combination of a base having a pointer, a pairof plates slidably mounted thereon and each having a pointer, a pivotbetween the plates, an operating member mounted intermediate its ends onthe pivot and having a cylindrical lug at one end extending down betweensaid plates and having a slot in the other end, a lug slid able in saidslot and extending down between the plates, and means for moving saidadjustable lug.

4. In a range finder, the combination of a base having a pointer, a pairof plates slidably mounted thereon and each having a pointer, a pivotbetween the plates, an operating member mounted intermediate its ends onthe pivot and having a cylindrical lug at one end extending down betweensaid plates and also having a longitudinal slot in the other end, a nutslidable in the slot, a screw to move the nut, and a cylindrical lugextending from the nut between said plates.

5. In a range finder, the combination of a base having a pointer fixedthereto, a pair of laterally movable pointers mounted on the base,adjustable means for positioning said movable pointers relative to thepointer on the base, and a scale graduated for different ranges todetermine the adjustment of the pointer positioning means.

6. In a range nder, the combination of a stationary pointer and twomovable pointers, means to ,support the pointers, one of the movablepointers and the stationary pointer constituting a measuring device andthe other movable pointer and the stationary pointer constitutingapredicting device, operating members for said devices of which theoperating member for the predicting device is adjustable, and a scalebar graduated for ranges to govern the operating member for thepredicting device.

7 In a range finder, the combination of a base, a fixed pointer and twomovable pointers mounted on the base, means to position one of themovable pointers relative to the stationary pointer to indicate thedistance traveled by a moving target between regular periods ofobservation, and adjustable means to position the other movable pointerrelative to the stationary pointer to indicate the distance the movingtarget will have traveled by the time it is reached by a projectile iredat the next period of observation, the distances being represented bywhere A is the distance indicated by the second movable pointer, B thedistance indicated by the first movable pointer, a the time of flight ofthe projectile and c the time interval between observations.

8. In a range iinder, the combination of a base, a pair of movabledevices mounted on the base, one to indicate the distance traveled by amoving target between the last two regular periods of observation andthe second to indicate the distance the target will have traveled by thetime it is reached by a projectile fired at the next period ofobservation, a lever pivoted intermediate its ends, one arm of the leverengaging the first movable device and being of constant length, the

other arm engaging the second movable device and being of variablelength, its length being ular periods of observation and the second to lindicate the distance the target will have traveled by the time it isreached by a proa jectile fired at the next period of observation, alever pivoted intermediate its ends, one

arm of the lever engaging the irst movable device and being of constantlength, the other arm engaging the second movable device and being ofvariable length, its length being represents the time of flight of theprojectile to the target and c the time interval between observations,said lever being graduated for different ranges.

10. In a range iinder adapted to be lused with a plotting board uponwhich locations of moving targets at predetermined intervals of time maybe indicated, a supporting device and an indicator adapted to bepositioned on said plotting board by the plotted location of the targetat the last observation, a second and a third indicator mounted on thesupport and movable relative to the first, and operating means mountedadjacent said times the length of the other arm where a indicators andhaving two engaging portions adapted to contact with said second andthird indicators, one of said engaging portions being adjustable on theoperating member so that the relative movements of said second and thirdindicators may be varied so that when either the second or thirdindicator is positioned for the next to the last plotted position of thetarget, the other will locate the probable position of the target at theexpiration of a period of time equal to the next predetermined intervalof time plus the time of flight of a projectile fired at the end of suchinterval at the moving target, the adjustment of said movable engagingportion of the actuating member being determined by the speed of theprojectile and the range of the target at the last observed location.

l1. In a range finder adapted to be used with a plotting board uponwhich locations of moving targets at predetermined intervals of time maybe indicated, the combination of a support, an indicator on the supporting means whereby the relative movement of adapted to be positioned onsaid plotting the third indicator in respect to the second board by theplotted location of the target may be varied. at the last observation, asecond and a third In testimony whereof I have signed this 5 indicatoron the support movable relative to speciication.

the rst, and operating means for actuating the second and thirdindicators and compris- CHARLES MCN'AUGHTON FROST.

Copies of this patent may be obtained for ve cents each, by addressingthe Commissioner of latents, Washington, ID. G.

